Dec. 19, 1974: Build Your Own Computer at Home!

The January 1975 cover of Popular Electronics brought in lots of orders for the Altair 8800 computer kit. It also inspired a couple of young programmers to adapt Basic for it.

1974: The Altair 8800 microcomputer goes on sale. It doesn’t offer much, but it’s the small start of a big trend toward small things.

A small New Mexico company — with the big name of Micro Instrumentation and Telemetry Systems and the small name of MITS — manufactured the Altair as a do-it-yourself kit. At its heart was the Intel 8080 microprocessor, with the remarkable capacity of 8 bits, or 1 byte. (Later models used the 8080A.)

The kit offered a 256-byte memory, just about enough to contain one sentence of text. The Altair’s open, 100-line bus structure evolved into the S-100 standard.

Keyboard? Dream on. That was a few years in the future. Input was accomplished through the “Sense Switches” (I/O address 255), eight toggle switches on the left side of the front panel.

Display? More dreaming. Output was accomplished through LEDs on the front panel. LEDs, 1974: high tech, kiddo.

The Altair 8800 kit sold for just under $400 (about $1,900 in today’s money). If you wanted to forgo the case, you could get the kit for under $300. Or you could order the whole deal fully assembled: Old-Computers.com quotes a $595 price.

If you wanted to soup the thing up, MITS offered a few peripherals: a video card, a serial card for connecting to a terminal, a 64-KB RAM-expansion card and an 8-inch floppy drive. The floppies stored 300 KB each. Those were the days.

MITS founder Ed Roberts got the name Altair from the stellar destination in a Star Trek episode. The idea came from the young daughter of a Popular Electronics magazine editor.

Popular Electronics heralded the amazing gadget on its January 1975 cover. Right away, orders started pouring in.

News of the Altair 8800 excited Paul Allen and Bill Gates, who wrote the first microcomputer Basic for the 8800 and, within months, went on to found Microsoft together.

MITS sold more than 2,000 Altairs by the end of 1975, beyond Roberts’ wildest expectations. IMS Associates, which sold the remarkably similar IMSAI 8080 microcomputer, shipped 50 that year.

But the Altair inspired more than knockoffs. The Commodore PET, complete with keyboard and monitor, debuted in early 1977. The Apple II came out later that year.